A sale
Open POS. Scan or search for items, and they build up on the ticket. Change quantities as needed, take payment, and the receipt prints or is emailed.
Stock reduces, the sale appears in reports, and the ledger entry is written for you.
Payment
Take cash, card, or a split across both. Record what was actually tendered - if a customer pays part cash and part card and you record it all as cash, the till will not reconcile and somebody will spend an hour looking for the difference.
Discounts and offers
Discounts are applied at the till by the cashier, within the limits their role allows. Offers are rules set up in advance - a promotion on a product or category - and apply themselves.
Prefer offers over manual discounts for anything planned. A promotion applied by hand depends on every cashier remembering it, and shows up in reports as a cashier giving money away rather than as a campaign you ran.
Returns
Process a return against the original sale wherever possible. That puts the stock back, refunds the right amount, and leaves a trail connecting the two. A refund typed in as a standalone negative is untraceable a week later.
Customers and khata
Customers records who you sell to. For regulars, that history is worth having.
Khata is credit: goods now, payment later. Record the sale against the customer, and record payments as they come in. The khata screen shows who owes what.
Credit is a loan you are making. The khata balance is real money that is not in your bank yet, and the longer it sits the less likely it is to arrive.
Shifts
Open a shift at the start, close it at the end, and count the drawer. The system tells you what should be there; the count tells you what is. Investigating a small difference on the day is easy, and a month of uncounted drawers is not.